.gitignore

@@ -0,0 +1,24 @@
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+bin
+
+# Test binary, built with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+
+# Dependency directories (remove the comment below to include it)
+# vendor/
+
+# Go workspace file
+go.work
+
+# General
+.DS_Store
+.idea
+.vscode

grpc.go

@@ -98,6 +98,7 @@ func (g *grpcClient) call(ctx context.Context, addr string, req client.Request,
 
 	maxRecvMsgSize := g.maxRecvMsgSizeValue()
 	maxSendMsgSize := g.maxSendMsgSizeValue()
+	cfgService := g.serviceConfig()
 
 	var grr error
 
@@ -116,6 +117,7 @@ func (g *grpcClient) call(ctx context.Context, addr string, req client.Request,
 			grpc.MaxCallRecvMsgSize(maxRecvMsgSize),
 			grpc.MaxCallSendMsgSize(maxSendMsgSize),
 		),
+		grpc.WithDefaultServiceConfig(cfgService),
 	}
 
 	if opts := g.getGrpcDialOptions(opts.Context); opts != nil {
@@ -218,6 +220,7 @@ func (g *grpcClient) stream(ctx context.Context, addr string, req client.Request
 
 	maxRecvMsgSize := g.maxRecvMsgSizeValue()
 	maxSendMsgSize := g.maxSendMsgSizeValue()
+	cfgService := g.serviceConfig()
 
 	grpcDialOptions := []grpc.DialOption{
 		g.secure(addr),
@@ -225,6 +228,7 @@ func (g *grpcClient) stream(ctx context.Context, addr string, req client.Request
 			grpc.MaxCallRecvMsgSize(maxRecvMsgSize),
 			grpc.MaxCallSendMsgSize(maxSendMsgSize),
 		),
+		grpc.WithDefaultServiceConfig(cfgService),
 	}
 
 	if opts := g.getGrpcDialOptions(opts.Context); opts != nil {
@@ -369,6 +373,17 @@ func (g *grpcClient) newCodec(ct string) (codec.Codec, error) {
 	return nil, codec.ErrUnknownContentType
 }
 
+func (g *grpcClient) serviceConfig() string {
+	if g.opts.Context == nil {
+		return DefaultServiceConfig
+	}
+	v := g.opts.Context.Value(serviceConfigKey{})
+	if v == nil {
+		return DefaultServiceConfig
+	}
+	return v.(string)
+}
+
 func (g *grpcClient) Init(opts ...client.Option) error {
 	if len(opts) == 0 && g.init {
 		return nil
@@ -826,7 +841,6 @@ func NewClient(opts ...client.Option) client.Client {
 	}
 
 	rc.pool = NewConnPool(options.PoolSize, options.PoolTTL, rc.poolMaxIdle(), rc.poolMaxStreams())
-
 	c := client.Client(rc)
 
 	// wrap in reverse

options.go

@@ -25,6 +25,9 @@ var (
 	// DefaultMaxSendMsgSize maximum message that client can send
 	// (4 MB).
 	DefaultMaxSendMsgSize = 1024 * 1024 * 4
+
+	// DefaultServiceConfig enable load balancing
+	DefaultServiceConfig = `{"loadBalancingPolicy":"round_robin"}`
 )
 
 type poolMaxStreams struct{}
@@ -115,3 +118,14 @@ func CallOptions(opts ...grpc.CallOption) client.CallOption {
 		o.Context = context.WithValue(o.Context, grpcCallOptions{}, opts)
 	}
 }
+
+type serviceConfigKey struct{}
+
+func ServiceConfig(str string) client.CallOption {
+	return func(options *client.CallOptions) {
+		if options.Context == nil {
+			options.Context = context.Background()
+		}
+		options.Context = context.WithValue(options.Context, serviceConfigKey{}, str)
+	}
+}